One of the recently characterized Ro/SS-A (Ro) genes encodes a 52 kD autoantigen that contains a zinc finger motif. The 52 kD Ro protein's novel zinc finger motif has significant homologies with sequences found in a number of DNA binding proteins. Zinc finger motifs have been described in numerous DNA binding proteins, most of which have gene regulatory functions. To test the hypothesis that 52 kD Ro is a DNA binding protein, DNA cellulose binding experiments were conducted. The results reveal that the native and recombinant 52 kD Ro proteins bind DNA with high affinity and in a zinc-dependent fashion. Whole genome polymerase chain reaction methods were utilized to isolate human genomic DNA fragments that are specifically bound by the 52 kD Ro protein. Naturally occurring Ro autoantibodies prevent 52 kD Ro protein from binding DNA. Studies are now proposed to characterize the DNA sequences that are bound by the 52 kD Ro protein, and to authenticate the DNA binding sites by using synthetic oligonucleotides in competitive binding experiments and gel shift assays. The target sequence(s) will be compared to previously characterized regulatory elements. Genes that contain these target sequences will be identified by searching the DNA databases or if necessary by screening a human genomic DNA library. Gene fragments that contain the target sequence will be subjected to competitive binding assays, gel shift assays and (or) DNase protection assays to confirm that the 52 kD Ro protein binds to them. Transfection studies will investigate the cellular effects caused by over-expressing the 52 kD Ro protein in human cells. These studies will: 1) determine DNA sequence(s) bound by the 52 kD Ro antigen; 2) identify genes whose expression is regulated by the 52 kD Ro antigen; and 3) elucidate the cellular function of the 52 kD protein. The outcome of these studies should have a significant impact on our understanding of the role that this autoantigen plays in the Ro autoantibody-associated immune disorders and thus may expedite the development of better strategies for treating those afflicted.